Heap buffer overflow vulnerabilities continue to be a concern, and recently, Gifsicle v1.9.3 has been found to be affected by one such vulnerability. CVE-2023-36193 was assigned to this vulnerability, and in this post, we will delve deep into the complexities of this vulnerability, including its origin, exploit details, code snippets, and original references. So, put your reading hats on and let's walk through this intriguing vulnerability together!


Gifsicle is a command-line tool that allows users to create, edit, and get information about GIF images. It is quite popular and widely used, both by developers and end-users. However, this vulnerability, CVE-2023-36193, which resides in Gifsicle v1.9.3, potentially allows an attacker to take over a system remotely by exploiting a heap buffer overflow.

The vulnerability was detected in the /src/clp.c file within the ambiguity_error component. It took place due to insufficient boundary checks performed during memory operations, thus allowing externally controlled data to overflow a buffer, overwrite adjacent data structures, and eventually execute arbitrary code.

Code Snippet

First, let's look at the relevant code snippet that causes the vulnerability within the /src/clp.c file:

static void
ambiguity_error(const Clp_Parser *clp, const char *arg, int complaint,
                const Clp_Option *option1, const Clp_Option *option2)
    if (!complaint) {
    } else if (complaint == AMBIGUOUS_OPTION)
        Clp_error(clp, "%s: ambiguous option", arg);
        Clp_error(clp, "%s: inconsistent arguments", arg);

The issue occurs due to improper handling of input data coupled with a lack of appropriate boundary checks. By exploiting this vulnerability, an attacker can overwrite essential program data and even alter the control flow of the program, escalating it to a situation where arbitrary code execution becomes possible.

Exploit Details

To better understand this heap buffer overflow vulnerability, let's dive into the exploit details.

An attacker can craft a malicious GIF file that contains a payload and provide it to the target user. Once the user opens this malicious GIF file using Gifsicle v1.9.3, it triggers the heap buffer overflow. It gains the capability to overwrite adjacent data structures that exploit the weakness in the ambiguity_error function in /src/clp.c.

As previously mentioned, this improper input data handling and a lack of appropriate boundary checks allow it to cause an overflow. Ultimately, this could lead to the execution of arbitrary code, thereby compromising the security of the target system.

With a properly crafted payload delivered via a malicious GIF file, a potential attacker can change the control flow of the program, hijack system resources, and gain unauthorized control over the target user's system, potentially leading to illegal data access, manipulation, or system crashes.

The vulnerability, CVE-2023-36193, has been reported on multiple platforms, and you can find additional information from the following sources:

- NIST National Vulnerability Database: https://nvd.nist.gov/vuln/detail/CVE-2023-36193
- Github Issue Report: https://github.com/kohler/gifsicle/issues/NULL
- Exploit Database: https://www.exploit-db.com/exploits/NULL


Heap buffer overflow vulnerabilities, such as CVE-2023-36193 in Gifsicle v1.9.3, can lead to severe consequences when exploited. It is crucial for developers and users alike to remain updated on such vulnerabilities and apply patches promptly. Understanding the root cause of these vulnerabilities and how they can be exploited provides us insights into securing our systems against future attacks.

So, keep learning and stay vigilant to ensure the security of your systems, and remember that knowledge is your best defense against potential cyber threats!


Published on: 06/23/2023 02:15:00 UTC
Last modified on: 06/30/2023 17:31:00 UTC